Front Page

Previous Story

Next Story

NIH Record vertical blue bar column separator

Intuition vs. Reason
Nobel Laureate Kahneman Posits Two Forms of Thought in WALS Talk

By Rich McManus

On the Front Page...

Every talk in the Wednesday Afternoon Lecture Series (WALS) is, of course, interesting, but some talks are more interesting than others. Dr. Daniel Kahneman's Mar. 3 lecture, which he titled "A Perspective on Intuitive Thought," was especially provocative and fun because it dealt not with biological minutiae but with phenomena common to everyday life: reading the emotions on the other end of a phone conversation, figuring out whether presidential poll results are hogwash or meaningful, deciding if a stranger on the sidewalk is a threat or harmless.


Dr. Daniel Kahneman
Clearly, Kahneman, who is Eugene Higgins professor of psychology at Princeton University and the 2002 winner of the Nobel Prize in economics, has given a lot of thought to how humans think and judge. Intuition, he argued, is responsible for both marvels and illusions; he joked that he specializes in pointing out its flaws. The good thing about intuition, he said, is that it is quite often accurate, and takes a long time to form. The bad part is that it can not only be erroneous, but also "the errors are very difficult to correct."

He started simply by illustrating what he called "the accessibility problem." First he flashed a math equation: 17 x 24 = 408. Few in the audience would bother to actually do the math, he predicted; the answer seems at least ballpark-true. Next he flashed, "Vomit is disgusting." It takes no reflection at all to agree with that, no mental "work." It is intuitively true.

Not all intuition is easily won. Chess masters, for example, must play an average of 10,000 hours of the game to develop expertise. But that investment of time equips them with a "vision" of how to play, of how to see the consequences of multiple steps into the future. Fire chiefs, too, said Kahneman, develop mastery in sizing up risk and response to blazes, and can decide almost instantly how to handle fires. Psychologists call the fireman's power "recognition-primed decision-making...When you ask them later why they behaved as they did, very often they are not conscious of having made a decision — they simply chose the first solution that came to mind," said Kahneman. "They recognized what needed to be done."

Expertise grows best with prolonged practice that includes rapid and unequivocal feedback, and that features reliable signals of threats and opportunities. "These conditions, however, are not always fulfilled," Kahneman said. When they are not, flaws can emerge in intuition, leading to "overconfident experts and false impressions."

He reviewed several decades of psychology experiments, many very cleverly designed, showing intuition's clay feet, its tendency to make too much of sparse sample data. Hubris, it turns out, is intuition's great sin — a tendency to pair very poor accuracy with blazing confidence. "People are poor at assigning weight to evidence," he observed via studies of political and economic forecasting in which intuitive thinking fared reliably and stubbornly poorly against predictive equations. Further damning the intuitive mode of thought is its resistance to education; those in its thrall "have little ability to learn from their mistakes," Kahneman observed.

He proposes a model of intuitive thinking "that can accommodate both its flaws and its marvels," he said. There are two basic families of thought processes: 1) intuition and 2) reasoning. The former is fast, automatic, parallel, effortless, associative, slow-learning and emotional. The latter is slow (in the ruminative sense), serial, controlled, effortful, rule-governed, flexible and (emotionally) neutral.

"Basically, we run on system 1," Kahneman said. "We don't work very hard." The appeal of this mode is that it's "unproblematic, skilled and adequately successful...One physiological sign that the mind is working hard is that the pupils dilate, and I don't see many pupils dilating out there in the audience," he quipped.

How do you tell if you're in system 2 versus system 1? Kahneman posited an "effort diagnostic." You're definitely in system 2 if interruption by a concurrent activity — say someone practicing trumpet while you're trying to read the paper — proves irritating.

Illustrating how the mind shifts from light attention to more concentrated effort is a simple math problem: A bat and ball cost $1.10. The bat costs a dollar more than the ball. How much does the ball cost?

Fifty percent of Princeton undergrads (and a slightly lower percentage of MIT students, Kahneman said) flub this question by reflexively answering, "Ten cents." Further attention to the terms of the problem reveals the correct answer — a nickel. The error, Kahneman argues, is due to "light monitoring" by the mind.

All of which returns us to the idea of accessibility — the ease with which thoughts come to mind.

Kahneman calls his theory of mind an "evolutionary speculation." He claims that the intuitive system is an adaptation of human perceptual systems, including seeing, hearing, and all the modes by which we understand the world. He showed that context determines how we interpret the things we perceive, and that our minds often rush toward single interpretations while actively suppressing alternative interpretations. "Doubt," he stated, "is a product of system 2." So is consideration of the possibility of alternate perceptions. "We don't compute everything we could compute," he summarized.

Through a series of slides and other examples, he showed that perceptual rules determine how we see the world and that "very close analogs to these rules apply to thinking."

His continual warning, as he described various psychology experiments, was that "very often we're not aware of cases in which our intuition is leading us astray...Very little can be done about this...Sometimes we can recognize situations when intuition is leading us the wrong way, but the process is slow, laborious, difficult and costly."

But there was nothing gloomy about this sober assessment. In fact, the questions after Kahneman's lecture were as interesting as his talk: Are men more logical than women? "Clearly there are gender differences in cognitive processing, but that makes no difference in what I presented here." Are groups better than individuals in making decisions? "They make things worse about as often as they make things better." Groups are characterized often by shared bias and shared erroneous intuition, Kahneman said. "So they can make decisions more polarized, more extreme, more overconfident." Is adhering to a doubtful world view simply a developmental stage? "People can acquire discernment," Kahneman allowed, but our bent is to rush to a coherent, unquestioned picture of the world in which we don't consider the possibility of error.

If this kind of talk is your cup of tea, watch the whole thing at

Up to Top